Multiplex distributor



United States Patent z,794,ssz

MULTIPLEX DISTRIBUTOR Frank J. Calderone, Jr., Yonkers, N. Y., assignerto The Western Union Telegraph Company, New York, N. Y., a corporationof New York Application November 18, 1953, Serial No. 392,313

Claims. (Cl. 178-52) This invention relates to improvements in telegraphsignaling and more particularly to an improved segment arrangement formultiplex distributors.

In the transmission of messages over a cable, each impulse will causeenergy to be absorbed and stored in the cable due to its capacitivecharacteristics. A portion of this absorbed energy is propagated towardthe receiving terminal. in transmission the message signals at thereceiver are distorted by the characteristics of the cable. It has longbeen recognized that a grounding interval between successive signalpulses will help minimize this distortion. ing as it has come to beknown in the art, permits the stored energy from the preceding signalpulse to be dissipated by the cable resistance. Much of this storedenergy is dissipated in the portion of the cable in the vicinity of thetransmitter. The result of this is that smaller amounts of the lowfrequency components, which cause the recording distortion, do not reachthe receiver. The advantages obtained from employing curbing areespecially apparent in high speed transmission as when automatictype-printing machines are used. In such systems an interval betweeneach impulse is needed to permit the discharge by the cable of thecharge put thereon by the preceding impulse. Thus the cable isneutralized after each impulse in preparation for the succeeding one.

The result of this type transmission makes it possible to obtain highersignaling speeds which is of prime importance as an economy factor. Theduration of the curbing interval may govern the signaling speed. Ingeneral, a larger curbing interval will make possible greater speeds. Inmultiplex typeprinting systems the necessity for curbing exists becauseof the high speed of transmission, and hence the advantages discussedabove are particularly applicable.

In such systems, curbing is generally achieved by dividing thedistributor ring into alternate sending segments and curbing segments.The curbing segments are connected together and grounded. The sendingbrush in traversing the distributor ring will thereby ground the cablebetween successive message impulses. Inasmuch as the sending brush mustnot be permitted to fall into the gap that electrically isolatesadjacent segments, the brush must be of such width as to bridge thisgap. With a double current ground return arrangement as employed in themodern telegraph system, the battery or other source of potential wouldbe directly shorted during the time that the sending brush bridges anytwo adjacent segments, resulting in high current and arcingv at thesegments. In order to prevent this arcing and the consequent destructionof the segments, a battery tap resistor is customarily inserted in eachbattery circuit, and a curbing resistor is employed to couple thecurbing Segments to ground. While the battery tap resistor effectivelyaids in limiting the shorting current to prevent arcing, it presents thedisadvantage of also limiting the transmission current.

It is therefore an object of this invention to provide This periodicgrounding of the cable, or curb-` 2,794,852 Patented June 4,

a telegraph system employing a segmented distributor wherein segmentarcing is eliminated without a decrease of transmission current.

Another object of this invention is to provide an improved distributorface plate.

Another object of this invention is to eliminate arcing between segmentsof a telegraph distributor.

A further object is to obtain maximum transmission current in amultiplex telegraph system.

These and other objects will become apparent from the followingdescription taken in view of the drawings in which:

Fig. 1 is a diagrammatic representation of a portion of a distributorring and battery connections of a system of the prior art, which isillustrated to aid in the understanding of the present invention;

Fig. 2 is a schematic diagram of a two-channel multiplex transmittingterminal employing the principles of the present invention; and

Fig. 3 is an enlarged development of a portion of the distributor ofFig. 2.

Referring now to Fig. l, sending segments 10 and 11 are separated bycurbing segment 12 which is grounded through curbing resistor 13. Abrush 14 connected to the cable circuit (not shown) is caused totraverse the segmented ring. Each sending segment has a positive ornegative potential selectively applied thereto. As seen in Fig. 1,battery 15 is supplying a negative potential to sending segment 11. Asthe brush passes from segment 11 to curbing segment 12, the gap betweenthese segments is momentarily bridged and current flows from ground,through battery 15, resistor 16, segment 11, brush 14, segment 12,resistor 13 back to ground. This current, which tends to cause arcing,is limited by resistor 16. However, as is readily apparent, thisresistor will also serve to limit the sending current since it isdirectly in series with the battery and cable when brush 14 is fullycontacting segment 11.

With improved cable system design employing submerged repeaters, highersignalling speeds are made possible. The higher frequencies resultingtherefrom will be subject to greater attenuation than relatively lowerfrequencies, making it necessary to use a battery of higher potential.The bridging current that would result from the larger battery must ofcourse be limited by a relatively larger battery tap resistor. However,this larger resistor in the battery circuit will cause a proportionatelygreater decrease in sending current. It is seen therefore that thedesirability of having the battery tap resistor approach zero is everpresent but especially necessary at higher frequencies.

Referring now to Fig. 2, there is shown a two-channel multiplextransmitting terminal comprising a distributor 17 and two transmitters18 and 19. The transmitters may be of any conventional type such as akeyboard or tape controlled machine employing the well known veunitcode. A distributor ring 21 is divided into alternate sending segments22 and open segments 23 insulated from each other. In the embodimentillustrated, there are ten sending segments and ten open segments, thenumber being a function of the number of channels for which the systemis designed. The ve center contacts of transmitter 19 are connected bywires 24 to live successive sending segments 22 of `the distributor ring21. Transmitter 18 is similarly connected to the remaining segments 22of ling 21. Another segmented ring 2S which for purposes of descriptionwill be called the curbing ring comprises alternate curbing segments 26and open segments 27 suitably insulated from each other. The curbingsegments are joined by wire 28 and grounded. A third contact ring 29 isconnected by wire 31 to outgoing cable 32. A sending capacitor 33 isinterposed in the output circuit to effect signal shaping by presentinga progressively higher impedance to lower frequency components. A brusharm 34 of conductive material is caused to rotate in a well known mannerto cause brushes 35, 36 and 37 to `traverse the contact rings as shown.

Referring now to Fig. 3, portions of the rings 29, 21 and 25 are shownin development. It is seen that curbing ring 25 is so constructed thatthe curbing segments 26 are somewhat shorter than the open segments 23of distributor ring 21 and are centered with respect to segments 23. Thewidth of the air gap between any two adjacent segments is less than thewidth of the brushes in accordance with conventional practice to preventthe brush from descending into the `gap in passing from one segment tothe next. The distance d between the trailing edge 2,2/1 of a sendingsegment 22 and the leading edge 26a of a curbing segment 26 is madegreater than the width of the brushes. As the brushes move from right toleft as viewed in Fig. 3, brush 36 will ride off sending segment 22before brush 37 contacts with curbing segment 26. Since these twosegments are at no time bridged, arcing and fiashover is prevented. Thesame spacing and action occurs between the trailing edge of the curbingsegment and the leading edge of the succeeding sending segment. Thus, itwill be noted that a small interval. exists at each end of a sendingpulse during which the cable ring 29 is disconnected from both thesending segment 22 and the curbing segment 26. It is desirable thatthese intervals be kept as short as possible in order to realize themaximum transmission time per revolution. Therefore, though d may be anysize greater than brush width for purposes of preventing arcing, inpractice d is made just slightly greater than the width of the brushes.The braided copper brushes commonly used will wear to a width of from.020 inch to .030 inch. It has been found that a distance d of .040inch, thereby producing an interval of at least .010 inch during whichthe cable ring 29 is disconnected from both the curbing segment andsending segment, gives highly satisfactory results. Arcing is preventedand the interval is of negligible proportion relative to the duration ofan impulse.

The cable 32 is connected to a distributor at the receiving terminalwhich is of identical construction as sending distributor 17. Thedistributor or face plate of the present invention is therefore equallyapplicable as a sending distributor and receiving distributor.

It will be appreciated from the above description that the battery tapresistor of prior art systems is eliminated by the face platearrangement of the present invention. This feature should be especiallynoted since it makes possible the greater transmitting current requiredby high speed systems. The high frequencies of such systems are subjectto greater attenuation and hence require a battery source of greaterpotential. If it were necessary to resort to a battery tap resistor toprevent arcing, the loss in sending current would be of an order thatwould limit the high frequency transmission. The present invention,however, in effecting a battery tap resistance that approaches zero,permits signaling speeds that would otherwise be unobtainable.

While the present invention has been disclosed with reference to aspecific embodiment thereof, it is understood that this is not to beconsidered as limiting the appended claims.

What is claimed is:

l. A distributor adapted to be employed with a telegraph systemcomprising a first segmented ring with an insulating gap betweenadjacent segments and wherein alternate message segments are adapted tobe connected to message operating means, a second segmented ring with aninsulating gap between adjacent segments and including alternate curbingsegments corresponding to said message segments of said first ring, eachof said message segments being angularly displaced with respect -to thecorresponding curbing segment, means to traverse said first and secondrings, said traversing means being wider than the said gaps betweensegments, the distance from the trailing edge of a message segment tothe leading edge of a curbing segment and the distance from the trailingedge of a curbing segment to the leading edge of the next succeedingmessage segment each being greater than the width of said traversingmeans.

2. A distributor adapted to be employed with a telegraph systemcomprising a first segmented ring with an insulating gap betweenadjacent segments and wherein alternate message segments are adapted tobe connected to message operating means, a second segmented ring with aninsulating gap between adjacent segments and including alternate curbingsegments corresponding to and angularly displaced from said messagesegments of said first ring, means to traverse said first and secondrings, said traversing means having a width greater than the gapsbetween said segments, the angular distance from the trailing edge of amessage segment to the leading edge of a curbing segment being greaterthan the angle subtended by said traversing means and the angulardistance from the trailing edge of a curbing segment to the leading edgeof the next succeeding message segment being greater than the anglesubtended by said traversing means.

3. A distributor for use with a telegraph system comprising a firstsegmented ring including alternate message segments and open segmentswith an insulating gap between adjacent segments, a second segmentedring including alternate curbing segments and open segments with aninsulating gap between adjacent segments, each of said message segmentsof said first ring corresponding to a curbing segment of said secondring, and means of a width greater than said insulating gaps to traversesaid first and second rings, said curbing segments being angularlydisplaced with respect to the corresponding message segments and of suchrelative lengths that said traversing means rides off each messagesegment before contacting the corresponding curbing segment and ridesoff each curbing segment before contacting the next succeeding messagesegment.

4. A distributor for use with a telegraph system comprising a firstsegmented ring including alternate message segments and open segmentswith an insulating gap between adjacent segments, a second segmentedring including alternate curbing and open segments with an insulatinggap between adjacent segments, each of said message segments of saidfirst ring corresponding to a curbing segment of said second ring androtatable contact means of a width greater than said insulating gaps totraverse said first and second rings, said message segments being ofsuch relative lengths and located with respect to the correspondingcurbing segments whereby said rotatable contacting means breaks contactwith each message segment before contacting the corresponding curbingsegment and breaks contact with each curbing segment before contactingthe next succeeding message segment.

5. A multiplex distributor for use with a telegraph transmittercomprising a first segmented ring including alternate sending segmentsand open segments with an air gap between adjacent segments, a secondsegmented ring including alternate curbing and open segments with an airgap between adjacent segments, each of said sending segments of saidfirst ring corresponding to a curbing segment in said second ring androtatable contact means of a width sufficient to bridge said air gaps totraverse said first and second rings, said sending segments being ofsuch relative lengths and located with respect to the correspondingcurbing segments whereby said rotatable means breaks contact with eachsending segment before contacting the corresponding curbing segment andbreaks contact with each curbing segment before contacting the nextsucceeding sending segment.

6. In a telegraph system comprising a sending distributor for applyingintelligence signals to a cable, a first segmented ring includingalternate sending segments and open segments with an air gap betweenadjacent segments, a second segmented ring including alternate curbingsegments and open segments with an air gap between adjacent segments,each of said sending segments of said first ring corresponding `to acurbing segment in said second ring and angularly displaced with respectthereto and rotatable contact means of a width greater than said airgaps connected to said cable and adapted to traverse said first andsecond rings, said sending segments being located with respect to thecorresponding curbing segments whereby the cable is alternatelyconnected to sending and curbing segments upon rotation of said contactmeans.

7. A multiplex telegraph system comprising a distributor for applyingsignals to a cable, said distributor comprising a rst segmented ringincluding alternate sending segments and open segments with an air gapbetween adjacent segments, a plurality of telegraph transmitters coupledto said sending segments, a second segmented ring including alternategrounded segments and open segments with an air gap between adjacentsegments, each of said sending segments of said first ring correspondingto a grounded segment in said second ring, and rotatable contact meansof a width larger than said air gaps connected to said cable and adaptedto traverse said first and second rings, said sending segments beingangularly located with respect to said grounded segments whereby thecable is alternately coupled to sending and grounded segments uponrotation of said contact means.

8. A distributor for use with a telegraph system comprising a rstsegmented ring including alternate message segments and open segmentswith an insulating gap between adjacent segments, a second segmentedring including alternate curbing segments and open segments with aninsulating gap between adjacent segments, said message segments andcurbing segments being angularly staggered and means to traverse saidirst and second rings, said means to traverse having a width larger thansaid insulating gaps and smaller than the angular distance from thetrailing edge of a message segment to the leading edge of acorresponding curbing segment.

9. A distributor adapted to be employed with a telegraph systemcomprising a first segmented ring including alternate message segmentsand open segments with an insulating gap between adjacent segments, asecond segmented ring including alternate curbing segments and opensegments with an insulating gap between adjacent segments, said rst andsecond rings being oriented so that each curbing segment is angularlycentered between successive message segments and rotatable means totraverse said rst and second means subtending an angle greater than theangle subtended by said insulating gaps and less than either the angulardistance between the trailing edge of a message segment and the leadingedge of a curbing segment or the angular distance between the trailingedge of a curbing segment and the leading edge of the next successivemessage segment.

10. A distributor for use with a telegraph system comprising a irstsegmented ring including alternate message segments and open segmentswith an insulating gap between adjacent segments, a second segmentedring including alternate curbing segments and open segments with aninsulating gap between adjacent segments and means to traverse said rstand second rings, said rings being so oriented that each curbing segmentis angularly located between successive message segments, said means totraverse subtending an angle larger than lthe angle subtended by thesaid insulating gaps and smaller than either the angle delined by thetrailing edge of a message segment and the leading edge of thecorresponding curbing segment or the angle dened by the trailing edge ofa curbing segment and the leading edge of the next successive messagesegment.

Knoop June 30, 1931 Kerr Dec. l, 1931

